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1.
    
Direct and label-free detection of unmodified DNA has always been a great challenge for DNA analyses. Surface-enhanced Raman spectroscopy (SERS) can provide structural fingerprinting of analytes with single-molecules sensitivity, so it could be the best candidate for label-free detection of DNA. Wild mushrooms, a very nutritious and delicious food in our lives, are widely distributed in Yunnan province. Herein, a simple and reliable method, based on SERS, was developed for label-free detection of DNA from six wild mushrooms and three common edible mushrooms. Concentrated Ag colloid prepared by microwave heating method with high SERS activity was used to obtain high reproducible SERS spectra. SERS signatures and spectroscopic band assignments of these mushrooms DNA were analyzed. Principal component analysis was used to distinguish these nine mushrooms. This experiment provides a simple and reliable method to detect mushrooms DNA, which is useful for the study of mushrooms DNA. Also, this approach has great potential for species identification of wild mushrooms and provides a basis for learning the interaction between DNA and small molecules. To our best knowledge, it is the first SERS study on DNA from wild mushrooms.  相似文献   

2.
    
Rapid and accurate diagnosis of cancers at early stage is clearly desirable, because it provides possibilities to cure the cancers in next treatments. Cancers at early stage usually occur and develop at a molecule level; however, it remains challenging for traditional methods to screen them timely. Here, the capability of using human blood serum surface‐enhanced Raman scattering (BS‐SERS) spectroscopy for label‐free, non‐invasive detection of liver cancer at the molecule level is presented. By using the solid device of silver nanofilms, we performed human BS‐SERS measurements of 40 liver cancer patients and 40 healthy controls and demonstrated a promising diagnostic algorithm for liver cancer detection based on the method of multivariate statistical analysis. The principal components analysis combined with independent sample t test were performed on these BS‐SERS spectral data, separating the cancerous samples from the normal ones with high‐diagnostic sensitivity of ~95.0% and diagnostic specificity of ~97.6%, respectively. This study demonstrates great potential in applications of label‐free, non‐invasive, and rapid human BS‐SERS detection for liver cancer at the molecule level.  相似文献   

3.
文中基于高效、生物兼容性纳米结构银膜,采用便携式拉曼光谱仪分别对10个健康人和10个急性粒白血病患者的氧合血红蛋白进行了表面增强拉曼散射(SERS)光谱的研究。实验发现,健康人与急性粒白血病患者的氧合血红蛋白SERS光谱存在显著差异:(1)健康人氧合血红蛋白SERS光谱中位于340cm-1附近很弱的拉曼峰在急性粒白血病患者的SERS光谱中变的很强;(2)健康人氧合血红蛋白SERS光谱中位于655 cm-1附近的拉曼峰在急性粒白血病患者SERS光谱中蓝移到670 cm-1附近,同时在727cm-1附近出现一个新的拉曼峰;(3)对健康人和急性粒白血病患者氧合血红蛋白SERS光谱中位于472、814、1335、1423和1588 cm-1处的拉曼峰相对强度比研究发现,相对强度比I814/I472,I1335/I472、I1423/I472和I1588/I472可以作为较好的区分健康人和急性粒白血病患者的SERS光谱诊断指标,这为基于SERS光谱技术进行急性粒白血病诊断提供了初步实验依据。  相似文献   

4.
    
A simple method is demonstrated to detect DNA at low concentrations on the basis of surface‐enhanced Raman scattering (SERS) via polyvinyl alcohol‐protected silver grasslike patterns (PVA‐Ag GPs) grown on the surface of the common Al substrate. By the SERS measurements of sodium citrate and thymine, the PVA‐Ag GPs are shown to be an excellent SERS substrate with good activity, stability and reproducibility. With the use of the tested molecule of thymine, the enhancement factor of the PVA‐Ag GPs is up to ~1.4 × 108. The PVA‐Ag GPs are also shown to be an excellent SERS substrate with good biocompatibility for DNA detection, and the detection limit is down to ~10−5 mg/g. Meanwhile, the assignations of the Raman bands and the adsorption behaviors of the DNA molecules are also analyzed. In this work, the geometry optimization and the wavenumber analysis of adenine–Ag and guanine–Ag complexes for the ground states are performed using density functional theory, B3LYP functional and the LanL2DZ basis set. The transition energies and the oscillator strengths of adenine–Ag and guanine–Ag for the lowest six singlet excited states were calculated by using the time‐dependent density functional theory method with the same functional and basis set. The results show that the charge transfer in the adenine–Ag and guanine–Ag complexes should be the chemical factor for the SERS of the DNA molecules. Lastly, this method may be employed in large‐scale preparation of substrates that have been widely applied in the Raman analysis of DNA because the fabrication process is simple and inexpensive. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

5.
    
Combining membrane electrophoresis with surface‐enhanced Raman scattering (SERS) spectroscopy, the serum proteins were first purified and then mixed with silver nanoparticles to perform SERS spectral analysis. Therefore, the spectral signatures were enhanced to high‐fidelity SERS signatures because of the purification procedure of the first step. We used the method to analyze blood plasma samples from nasopharyngeal cancer patients (n = 43) and healthy volunteers (n = 33) for cancer detection. Principle component analysis of the SERS spectra revealed that the data points for the cancer group and the normal group form distinct, completely separated clusters with no overlap. Therefore, the nasopharyngeal cancer group can be unambiguously discriminated from the normal group, i.e., with both diagnostic sensitivity and specificity of 100%. These results are very promising for developing a label‐free, noninvasive, and reliable clinical tool for rapid cancer detection and screening. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

6.
    
There is a pressing need to improve the reproducibility of surface enhanced Raman spectroscopy (SERS) measurements, if the technique is to be used routinely for trace analysis. This is particularly true for colloidal SERS, in which data reproducibility is dominated by the final shape and size of metal clusters produced during colloid aggregation. This study presents general guidelines for designing appropriate measurement strategies that can be used to identify and optimise crucial steps in a protocol that leads to better reproducibility of the results. We show that the data reproducibility can be improved by optimising vortexing time during colloid aggregation, which we attribute to the formation of more reproducible metal clusters under conditions of ‘forced convection’. The study also investigated the effects of different storage conditions on the data reproducibility of SERS during a 6‐month study period. Storage conditions did not significantly influence the SERS reproducibility. However, at the end of 6 months, colloids that were stored (in plastic containers) at room temperature showed a difference in their quality, as mirrored by their different opto‐physical properties. This was made apparent through the analysis of UV‐vis spectroscopy measurements by principal component analysis. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

7.
    
Volatile fatty acids of acetic, butyric, lactic, and propionic acids play an important role in the methane fermentation process. Particularly significant amount of propionic acid presence in the process will influence the methane fermentation efficiency. Herein, zigzag-aligned silver nanorods were designed as surface-enhanced Raman scattering (SERS)-active substrates to establish the classification of volatile fatty acids against the traditional poor sensitive and time-consuming titration and gas chromatography methods. SERS and chemometric method of principal component analysis is used for the detection and classification of volatile fatty acids. Density functional theory calculations were performed to understand the Raman vibrations and compare with experimental observations and to aid in the assignments of spectral lines. For the first time, the authors have used SERS technique to classify the acids. The findings suggest that this method is of great potential in the field of methane fermentation from industrial waste.  相似文献   

8.
    
A unique, geometry‐optimized, surface‐enhanced Raman scattering (SERS) fiber‐optic sensor has been recently developed and built. Though this class of sensors can be very useful in many applications, their use is greatly hindered by the fact that their reusability can hardly be achieved because of the irreversible adsorption of the analyte molecules on the SERS‐active substrate. Different substrates have been tested on our sensor with the purpose of increasing its reusability by means of cleaning procedures or good reproducibility in manufacturing the sensor, keeping, however, the same enhancement. We show that a partial reusability of the sensor is possible using SERS‐active substrates prepared by a standard process of immobilization of silver nanoparticles with 3‐aminopropyltrimethoxysilane. We also show that a fairly good reproducibility can be achieved with a low‐cost substrate realized in a short time by depositing a layer of polyvinyl alcohol (PVA) containing silver nanoparticles on the etched fiber tip. We prove as well that measurements are possible even with nanoparticles dispersed in the analyte solution instead of using a substrate directly made on the sensor tip. Finally, we have successfully tested our sensor with some molecules cited in EFSA (European Food Safety Authority) and FDA (Food and Drug Administration) reports as molecules for which new detection methods are necessary. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

9.
基于核独立成分分析的人脸识别   总被引：1，自引：0，他引：1  
张燕昆  刘重庆 《光学技术》2004,30(5):613-615
研究一种基于核独立成分分析的人脸识别方法。利用支持向量机的核函数思想,将原始人脸图像向量映射到高维特征空间,然后在高维特征空间中进行独立成分分析(ICA),提取非线性独立成分作为特征向量进行分类识别。实验结果表明该方法要比常规的基于ICA和PCA的人脸识别算法的识别率要高。  相似文献   

10.
    
A simple fabrication method is demonstrated for surface‐enhanced Raman scattering (SERS)‐active plasmonic nanoballs, which consisted of Au nanoparticles (NPs) and core–shell polystyrene and amino‐terminated poly(butadiene) particles, by heterocoagulation and Au NP diffusion. The amount of Au NPs introduced into the core–shell particles increases with the concentration of Au NPs added to the aqueous dispersion of the core–shell particles. When the amount of Au NPs increases, closely packed, three‐dimensionally arranged and close‐packed Au NPs arrays are formed in the shells. Strong SERS signals from para‐mercaptophenol adsorbed onto composite particles with multilayered Au NPs arrays are obtained by near‐infrared (NIR) light illumination.  相似文献   

11.
    
We report the surface‐enhanced Raman scattering (SERS) effect from the apex of single‐crystalline Ag nanowires (NWs). We also fabricated tip‐enhanced Raman spectroscopy (TERS) tips by attaching individual Ag NWs to W wires by using the alternating current dielectrophoresis (AC‐DEP) method. The single‐crystalline Ag NW tips could overcome many of the shortcomings of conventional TERS tips. Most importantly, the results obtained from TERS using single‐crystalline metal NWs are very reproducible, and the tips are also reusable. This development represents a significant progress in making TERS a reliable optical characterization technique with nanometer spatial resolution. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

12.
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13.
    
In this article, a surface‐enhanced Raman scattering (SERS)–active substrate with great stability and usability is reported. It is composited with a two‐dimensional ordered array of Ag spherical caps and an aluminum coating. The ordered aluminum template formed during the synthesis of anodic aluminum oxide film was used as the patterned matrix. After sputtering a Ag layer and then peeling off the aluminum template, the patterned structure was replicated on Ag layer. The aluminum template could serve as a coating that protected Ag from being oxidized. Ultraviolet‐visible reflection measurement was performed to monitor the adsorption process of probing molecules. Taking 4‐mercaptopyridine as probing molecules, SERS spectra were investigated. Comparing with the ordinary Ag film, the patterned Ag layer exhibited better SERS activity. The convenience for preparing, storing, and using makes it a promising candidate for SERS application in the fast field analysis. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

14.
    
In this study, we demonstrate an easy particle‐mediated protocol using the specific structure of mesocrystal Ag2O sacrificial templates to synthesize highly rough‐cubic Ag mesocages. To the best of our knowledge, the mesocrystal particles are reported for the first time as sacrificial templates for synthesizing metal particles. The obtained Ag mesocages show high surface‐enhanced Raman scattering (SERS) sensitivity because of the highly rough topography formed by arrays of uniform individual Ag nanoparticles. Abundant “hot spots” with greatly enhanced local electromagnetic field are promoted densely on the mesocage surface by the plenty of deep and narrow gaps and the hollow structure. The single‐particle SERS signal generated by the Ag mesocage has an enhancement factor of approximately 109, which is approximately four times higher than the Ag mesocage synthesized using single‐crystal Ag2O particle as a template. Meanwhile, this signal displays a linear dependence on the detected analyte concentration, sensitively down to 1.0 × 10?12 m .  相似文献   

15.
    
Distinct cellular domains, such as structure–function compartments of the cell nucleus and cytoplasmic organelles, are responsible for numerous macromolecular processes essential for cell functions. Spectroscopic analysis of specific cellular domains opens a way for noninvasive characterization of their molecular content and monitoring of their function. Confocal Raman spectroscopy was employed here for characterization of the complex molecular organization of major structure–function compartment of the cell nucleus, the nucleolus. The Raman spectra obtained in the nucleoli were processed by biomolecular component analysis (BCA). BCA was used to determine the contribution of each major type of macromolecules (proteins, DNA, RNA and lipids) to the complex molecular composition of nucleoli. A notable cell‐to‐cell variability in the macromolecular composition of nucleolus was found. At the same time, we observed a correlation between the concentrations of major types of biomolecules in this nuclear compartment. In particular, the averaged concentration of RNA increases along with increase in protein concentration, while an inverse dependence between the concentrations of RNA and DNA was found. Variations in the nucleolar concentrations of lipids were also noticed. Manifestations in spectral variations of proteins for individual nucleoli, shown by BCA, are discussed and interpreted. We also compared utility of BCA and principal component analysis for biomolecular studies and conclude that BCA is a more powerful and informative technique for studies of macromolecular composition and its variations in specific subcellular domains. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

16.
    
This paper presents the application of Raman spectroscopy (RS) for the structural study of alizarin adsorbed on a metallic surface. As a biologically active molecule, alizarin has remarkable antigenotoxic activity like other anthraquinone dyes. Alizarin is highly fluorescent and that limits the application of RS as an investigation method; however, the Fourier transform‐RS (FTRS) can be applied since the near‐infrared excitation line lies far away from the absorption region of alizarin. The surface enhanced‐RS (SERS) technique also makes the fluorescence quenching possible. In this work, monolayers of alizarin were deposited on the surface of an electrode by the immersion of silver substrates in methanolic solution of the analyte. From such prepared samples, by using the excitation of 488, 514.5 and 647.1 nm the Raman spectra were registered. Depending on the excitation line, SERS or surface‐enhanced resonance Raman scattering (SERRS) spectra of alizarin were observed. The interpretation of experimental data was supported by theoretical calculations. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

17.
    
This work proposes a novel use of thin‐layer chromatography with detection by surface enhancement Raman spectroscopy (SERS) to generate chromatographic and spectral fingerprints of complex samples, aiming toward samples classification. Ten commercial beer brands were analyzed in order to verify clusters related to each brand and the brewery location. The samples were eluted in thin‐layer chromatography plates and sprayed by gold nanoparticles colloidal solution using a simple and cheap lab‐made apparatus. The plates were analyzed by SERS, so, at the end of the measurement, one SERS‐chromatogram matrix was acquired for each sample. The high sensitivity of the SERS analysis allows the detection of compounds in low concentrations, unseen via common thin‐layer chromatography detection procedures, increasing the information for fingerprint analyses. Because of the high complexity of the sample, coelution problems and slight shifts in chromatographic peaks might appear in this kind of analysis; it was necessary to use chemometric tools for data analysis. Two chemometric methods of data deconvolution were compared, multivariate curve resolution–alternating least squares and independent component analysis. From the chromatographic peaks recovered by both methods, it was possible to perform a fingerprint analysis using principal component analysis, which allowed identifying patterns among the samples according to the brands and brewery location of Pilsner beers produced in Brazil. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献   

18.
本采用Ｎｄ：ＹＡＧ１０６４ｎｍ激光器作为发光源并改进银胶制备方法获得了核黄素的工外表面增强拉曼光谱（ＮＩＲ－ＳＥＲＳ）。发现少量的氢氧化钠可提高核黄素的ＮＩＲ－ＳＥＲＳ增强因子,其检测限可达３．２×１０＾－１０ｍｏｌ·Ｌ＾－１。证实核黄素在近红外区比可见区有更强的增强因子。  相似文献   

19.
以质子酸功能化离子液体1-丁基-3-甲基咪唑磷酸二氢盐([Bmim]H2PO4)为反应介质和表面活性剂,采用简单的化学还原法制备了具有形状各向异性的块状银纳米颗粒。通过X射线衍射(XRD)、扫描电镜(SEM)、紫外-可见(UV-Vis)吸收光谱等一系列手段对其结构、形貌及光吸收特性进行了表征。结果表明,所制备的银纳米块具有立方结构,其平均横向尺寸约为30 nm,在硅片上自组装形成密堆积结构的多层膜。以1,2-二(4-吡啶基)乙烯(BPE)作为探针分子,研究所制备银纳米颗粒的表面增强拉曼散射(SERS)活性。结果表明所制的银纳米颗粒是较好的SERS基底,具有良好的增强效果,痕检能力及稳定性。对BPE分子的最低检测浓度可低至10-9mol·L-1,而且保存了90天后,其检测灵敏度没有显著的降低。  相似文献   

20.
利用银镜作为衬底,本文对乳酸钙的表面增强喇曼散射效应进行了研究.分析表明,乳酸钙分子在银镜上的吸附因缺少活位而不能产生明显的增强效应.Cl-的加入使得银镜表面活位得以稳定和增加,从而使乳酸钙在银镜衬底上显示出较强的增强效果.通过对混合溶液进行研究,发现乳酸钙和吡啶在银镜上的吸附相互独立,互不影响.  相似文献   

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